BYTNAR - TALKS
EPISODE 019 - APPROVED DOCUMENT B - FIRE SAFETY - VOLUME II - PART 2 OF 2
This episode is for people who want to know more about Approved Document Part B – Fire Safety.
You should like this episode if you ask yourself questions like:
What are the fire resistance requirements for load-bearing structural elements in buildings?
How does compartmentation work to prevent internal fire spread in multi-storey buildings?
When are sprinklers required for high-rise buildings according to Approved Document B?
What are the rules for installing cavity barriers to prevent fire spread in concealed spaces?
How should fire-stopping measures be implemented for penetrations in compartment walls?
What are the fire safety requirements for closed-sided car parks, including ventilation systems?
How does external fire spread prevention vary with building height and purpose?
What information must be included in fire safety documentation under Regulation 38?
What are the specific access and facility requirements for fire service operations in large buildings?
This is Bytnar Talks the Engineer Takes on Construction Episode 19 hi I'm Piotr Bytnar each day I help my clients plan and design building projects through Bytnar Limited a Consulting Chartered Structural Engineers practice my biggest passion and the corner stone on which I've built my business is find finding clever solutions for construction projects I am a chartered structural engineer and a bing software developer so you can rest assured that I will strive to talk about the best practices and the use of new technologies in the industry and if you're embarking on a construction project or are involved in planning designing and building the world around us you'll find this podcast useful approved document B fire safe volume two part two hi there and welcome back to Bitner talks your favorite podcast on all matters of architecture engineering and construction it is Thursday the 6 of June 2024 and I'm here back with you with the 19th episode and F information on fire safety in buildings other than dwellings today I will finalize talking about the approved document B fire safety volume two last week in episode 18 I introduced you to the requirements of the approved document and introduce you to the subject of warning and Escape as well as the fire spread through internal Linings so the requirements B1 and B2 covering sections 0 to six in general I told you that the volume two of the approved document B offers fire safety guidance for non-dwelling buildings for focusing on Life Safety over property protection and assuming proper management practices by building owners it includes considerations for inclusivity alternative safety approaches and special Provisions for specific buildings types like healthcare and historical buildings buildings are categorized into six purpose groups for risk assessment with stringent measures applied to mixed use buildings and complex situations potentially requiring fire safety engineering key requirements include adequate early fire Warning Systems safe Escape Routes and reliable fire detection systems alongside Provisions for horizontal and vertical escape and special rules for small premises the document also mandates that internal Linings resist flam spread and manage heat release ensuring adherence to ESS essential fire safety standards in this this episode I will cover requirements B3 to B5 and regulation 38 so without further Ado let's dive into the fire safety as treated in the approved [Music] document today I will talk about the guidance on provision of enough fire protection separation smoke and heat control and provision of enough fa facilities to enable firefighters to successfully undergo fire and rescue operations in the buildings other than dwellings in this material we will concentrate on the differences between the previous guidance seen in volume one considering Flats I will not reiterate the previous episode but extend on that knowledge or augment it in line with the requirement of volume two requirements B3 to B5 all right so let's dive in straight into it shall we so let's start with requirement B3 internal fire spread structure in the building shall be designed and constructed so that it in the event of fire its stability will be maintained for a reasonable period a wall common to two or more buildings shall be designed and constructed so that it adequately resist the spread of fire between those buildings for the purpose of this subparagraph a house in a Terrace and a semi Dage house are each to be treated as a separate building where reasonably necessary to inhibit the spread of Fire Within the building measures shall be taken to an extent appropriate to the size and intended use of the building comprising either or both of the following a subdivision of the building with fire resisant construction B Installation of suitable automatic fire suppression systems and point four the building shall be designed and constructed so that the Unseen spread of fire and smoke within the concealed spaces in its structure and fabric is inhibited so simple in a g the amount of consideration due will depend on The Purpose Group classification and the element considered but in any case the building structure needs to withstand the event of fire for a prescribed time without losing its stability the building should be compartmentalized to restrain the event of fire including openings automatic suppression system should be introduced where needed and unseen spaces and Cavities should be compartmentalized also to inhibit the spread of concealed fires and smoke so starting with Section seven loadbearing elements of structure most of the information on fire resistance is contain within appendix B including some special Provisions like the one of single story buildings that by their nature may not need any fire protection unless they support a compartment structure in such cases they need the protection of the same rate as of that compartment let's start with what is considered as an element of structure and what is not in Simple Times all that allows the building to stand and carry the envelope load and people at certain height is the element of structure all the rest is not things like roofs platform floors lowest floor of the building stage grids loading Gallery curtain walls and so on are not considered elements of structure an additional consideration for race storage areas is mentioned in that section also in circumstances where building does not otherwise need protection so single story storage building which by virtue of raised area could be come to story Section 8 deals with compartmentation and sprinklers walls and Floors separating buildings of different uses should be compartment walls unless the different uses anciliary to the main use stairs or service shaft connecting different compartments should be protected to restrict the spread of fire in any case of special fire hazard places these places should be enclosed with minimum of r fairy Construction in general the lowest flow in the building does not need to be a compartment flow but for the residential institutional including half care buildings and residential other buildings in non-residential buildings the consideration for compartmentalization follows the consideration of the floor area and height of the top story above or below the ground level level starting with no limits on compartmentation by flaws for buildings with flows up to 30 m ground level and basements up to 10 M below ground level but naturally basement needs to be separated from the top structure by fire resisant floow buildings over this limit will need to have compartment floors when it comes to the horizontal division offices and car Parks have no limits to the size of their compartments and otherwise the size varies between 2,000 square m in UNS sprinkled shops and up to 40,000 m in sprinkled storage and other non-residential buildings sprinklers are generally required in buildings with top story of a fair meter up in the air in respect of the compartmentation walls and flaws this should form a complete barrier and be of appropriate grate masonry compartment walls may be bridged by structural members but the penetration needs to be as small as possible fire stopped and the failure of structure on one side of the wall should not lead to the failure on the other side special consideration may be needed for services that could be a source of ignition compartment walls between buildings or separating parts of building need to extend the full height of the building in one vertical plane other compartment walls need to extend a full story in general compartment walls at the top story should be taken through the roof space Junction between the compartment elements or external wall should be integral and the and fire stopped in case the external wall has no fire resistance it should be attached to the floor to avoid flying flying off as the Phoenix rising from the ashes spreading the fire in the closed vicinity compartment walls need to be able to maintain Integrity even if the floor deflects due to the fire guidance even gives assumption to what level of deflection is appropriate at 40 mm midspan of the floor compartment wall Junctions with the roof are treated in the same way as for dwellings but the relaxation of the substrate classification that traverses the junction to the lower class is only possible in some buildings and under 50 m in height allowance for openings in compartment wall separating buildings or occupancies is given for the passage of pipes and fire doors the fire doors need to be of the same fire resistance as that of the wall and it needs to provide means of Escape in other compartment walls or floors the provision of appropriate fire doors pipe vents refu shoots protected shafts and arria is possible following guidance protected shaft made for whatever reason stairs Li du shoes or other should be of the construction that prevents spread of fire between compartments it traverses and itself be of appropriate build to resist fire be properly ventilated too a glazed screen can be provided between the stair and Lobby or Corridor provided the enclosure is not more than Ray 60 and the glazing screen is eir and complies with the dimensions restrictions and the corridor or Lobby is minimum r f enclosed otherwise the guidance refers us to appropriate tables in a pen XB there are Provisions for oil and gas pipes as well as the ventilation ducts in protected shafts and these need to be either separated from the shaft of certain material or serving the shaft only in addition if the pipe is a conveying is conveying flamable gas the shaft needs to be top bottom ventilated external walls of protected shafts do not usually need to be fire rated unless otherwise required by the virtue of its used like a firefighting Shaft or a protected stairway other openings in the protected shaft follow the consideration of similar penetrations as of that in compartment walls off to section nine cavities the provision of the guiders on cavities follows that of the volume one for Flats but extends ever so slightly with with the requirements of openings in cavity barriers provided over and and not fire rated partitions in residential buildings need to be kept to a minimum and any penetration should be smoke stopped and there is otherwise no more requirements for this as would be the case with cavity barriers that extend on the compartmentation cavity barriers forming parts of compartmentation have the rules but there is otherwise possibility of many large Hidden spaces without such compartmentation and these are ruled by maximum Dimensions depending on the material class of the enclosure that is exposed within the cavity so for cavities between the ceiling and the roof the maximum Dimensions Max maximum Dimension is 20 M no matter what the material but for other cavities it is either 20 M for materials Class C and beta and 10 m of all lower classes there are some exceptions from this rule like fully fitted cavities of cavity walls overcladding with material better than class bs3 D2 and others and that's it on cavities all the rest is same as for the floods section 10 directs us to protection of openings and fire stopping Provisions are generally the same as that found in the information provided for dwellings but guidance is a t more strict on the M material and size of penetrations of pipes Through Fire separating elements and there is a section that deals with situation where there is a risk of people sleeping in in this case appropriate arrangement for the activation of fire and smoke dumpers should be in place for Section 11 special Provisions for car Parks that's an additional section that's otherwise not in the volume one so in this document extra information is provided under the considerations for car Parks distinguishing between the ones that are open to the sides and ones that are closed it is considered that we know at what intensity the cars burn and that the risk of fire spreading between stories is little well vented spaces so dependent on ventilation the different circumstances the open-sided car park is a car park with no basements naturally ventilated at each level meaning at least 5% of the floor area is ventilation area to the sides but at least 1.25% of the flow area in opposite sides you know cross ventilation all material should be A1 rated expect for floors and roofs and some leware is provided on small facilities or areas immediately adjacent to it things like fire dorsets and iik naturally the aray for the car par structural elements needs to be at the level matching that for the supporting compartment if greater than that for the consideration of the car park alone otherwise consideration starts at 15 minutes which may allow some steel structure members to remain without protection for close- sighted car Parks the fire resistance needs to be between 30 and 120 Minutes for structural elements if there is at least 2 and a half% opening to the outside of which at least 0.625% so nearly a little bit more than a half% is in opposite ends the car park is considered naturally ventilated otherwise it will require mechanical ventilation mechanical ventilation needs to be separated for the car park and capable to achieve 10 air changes per hour during fire and be separated into two parts so when when one fail there is a residual 50% capacity in the system and capable to work of grid meaning with its own power supply outlet should be equally spread at high and low levels in addition the guidance directs us to British standards for the quality of tting and type of system so British standard 1366 for fire resistant test for service installations British standard 12101 smoke and heat control system NBS 7346 for components for smoke control systems and that's it for requirement B3 moving on to requirement B4 external fire spread let's start with a little bit of the legislation there's only two paragraph in that requirement but an addition of Regulation 7 is put in place and that one's quite long regarding materials and workmanship so let's start with requirement 4 paragraph 1 the external walls of the building shall adequately resist the spread of fire over the walls and from one building to another having regard to the height use and position of that building the roof of the building shall adequately resist the spread of fire over the roof and from one building to another having regard to the use and position of the building uh regulation seven which goes on to treat about materials and workmanship paragraph one building work shall be carried out with adequate proper materials which I appropriate for the circumstances in which they are used double I are adequately mixed or prepared and triple I are applied used or fixed so as adequately to perform the function for which they are designed and in a Workman like Mana 1 a building work shall be carried out so that relevant metal compos composite material does not become part of an external wall or specified attachment of any building two subject to paragraph three building work shall be carried out so that materials which become part of an external wall or specify attachment of a relevant building and I highlight here relevant building are of European classification A2 S1 d0 or A1 classified in accordance with the reaction to fire classification paragraph three paragraph two does not apply to and add a long list now a cavity trays when used between two leaves of masonry B any part of roof other than any part of a roof which Falls within paragraph four of Regulation 26 if that part is connected to an external wall which basically means slanted walls up to 70° C door frames and doors the electrical installations da Fiber Optic Cables e insulation and waterproofing materials used below ground level or up to 300 mmers above the level F in tacent and fire stopping material materials where the inclusion of the materials is necessary to meet the requirements of Part B of schedule one G membranes h seals gaskets fixing sealant and bucket roads H components associated with a solar shading devices excluding components whose primary function is to provide shade or deflect sunlight such as the owning curtain or slots I thermal brake materials where the inclusion of the material is necessary to meet the thermal bridging requirements of parel part L of schedule one J window frames and glass or k materials which form the top horizontal FL layer of a balcony which are of European classification A1 floor or A2 floor S1 classified in accordance with the reaction to fire classification provided that the entire layer has an imperforate substrate under it paragraph four in this regulation a relevant building means a building with a story not including roof Top plant areas or any story consisting exclusively of plant rooms at least 80 m above ground level and which I contains one or more dwellings double I contains an institution or triple ey contains a room for residential purposes and B above ground level in relation to a story means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the story well that was quite a bit wasn't it so you see in the G it is simple but has a lot of flavor in terms of exclusions if you listen to the episode treating on this requirement you are pretty much covert as most of the approach is universal and you are cordially invited to go and listen to episode 16 now section 12 resisting fire spread over external walls there are material use restriction that relate to the the external saf is starting at A2 or better for Relevant buildings en close to the boundary to see for buildings order than residential and assembly and recreational an additional consideration for the overcladding of masonry walls or cavity wall construction with solid inner Leaf Construction in terms of its buildup IS put in place and is required and it requires the inner side of the over clading or the external Leaf if you like it needs to be of a when it's of a sandwich type meaning the inner side needs to match the outside in terms of performance all the remaining aspects follows follow the guidance you can find in volume one of the approved document it's all about the internal surface not catching fire not being more sustainable to Catching Fire to that that is outside in section 13 resisting fire spread from one building to another again it is nearly entirely covered in volume one but some additional information you can find like in the case of large uncommented buildings when considering unprotected areas the areas over fa met above the mean ground level do not need to be taken in consideration and two approaches cover in BS quadruple 9 are the alternative approaches but guidance for Atria is the one especially recognize in the document section 14 resisting fire spread over roof covering I like how quickly we go through these points don't you if you recall the previous episodes it it was not that easy so do go back to revise as these expectations are the same and applicable here also there is nothing new to add to this section that is different from volume one so that's last part point last section to discharge requirement B4 now off to requirement B5 access and facilities for the fire service point one the building shall be designed and constructed so as to provide reasonable facilities to assist firefighters in the protection of Life two reasonable provision shall be made within the side of the building to enable fire appliances to gain access to the building so simple again and it is if you think about the reason behind it which is provision of enough access to allow for the fire and rescue operation most of the consideration of this is your safety at the time of emergency so may seem obsolete until they're not few points here there needs to be enough external access to enable fire appliances to be used here this may vary depending on the location so speak to your local fire rescue service to find out more in enough access to the building is to be provided enough access to internal fire facilities too and enough ventilation for heat and smoke to facilitate that access and operation and that's it let's see what the sections got to say section 15 deals with vhicle access so what do we need to do what do we need to do to provide enough access for typical firefighting Brigade with all the kit it all starts with typical consideration already covered in volume one of the document B so I will not reiterate this but we'll concentrate on differences the base of all consideration is the reach of typical firefighting appliances in the face of the building of a given size height and whether fir mans are fitted or not starting with no firan Mains building the requirement starts at 45 M but is limited to 15% of the perimeter of the building up to 2,000 M squared with the highest flow up to 11 m above ground level and goes up to 100% of the perimeter of the building over 24,000 M squared and over 11 M height limit under 11 M Floors reached by pumps and over 11 M by High Reach appliances the floor area is the sum of all stories not including basements perameter calculation excl excludes walls in common with other buildings but includes projections of stories over for fire Mains there is 80 M distance limit to inlets or Outlets either externally for inlets of dry Mains or of the entry point to the wet main but are also subject to consideration of section 16 and 17 access routs and hard standings requirement is bound to the side of the building and have the same considerations as the one for dwellings additional considerations are given to space adjacent to the hard standing to allow operation of turntable ladders or hydraulic platforms section 16 firemen and hydrant follow the same provision of volume one of the approved documents section 17 access to buildings for firefighting Personnel is a little bit extended in this section is ALS this section is also covered in volume one however the special Provisions for floods do not apply things like firefighting shaft incorporate all elements of the Escape Route including Lobby lifts and stairway encapsulating all three with Ray 120 Construction in addition the guidance recognizes that the need for the provision of at least two firefighting shafts for buildings under the 80 M floor level height bracket when that building is a shop and Commercial a assembly and recreational or industrial purposes group Building Group four five and six and when they have at least one story at a level higher than 7 and 1 half met over the fire rescue access level the story area consideration remains limited to 900 M square plus section 18 venting of heat and smoke from basement venting of heat and smoke from basement follows the same consideration of the volume one so I would like to return you back to the episode 17 of this podcast but when there is a basement car park the ventilation consideration discussed in section 11 is sufficient and that's done for the regulations for the requirements of requirements B let's mention the regulation 38 in the letter of law which is fire safety information fire safety information regulation 38 point one this regulation applies where building work a consists of or includes the erection or extension of a relevant building or B is carried out in connection with a relevant change of use of a building and Part B of schedule one imposes a requirement in relation to the work point two the person carrying out the work shall give fire safety information to the responsible person not later than the date of completion of the work or the date of occupation of the building or extension whichever is earlier point three in this regulation fire safety information means information relating to the design and construction of the building or extension and the services fittings and Equipment provided in or in connection with the building or extension which will assist the responsible person to operate and maintain the building or extension with reasonable safety b a relevant building is a building to which the regulatory reform fire safety order 2005 applies or will apply after the compettion of building work c a relevant change of use is a material change of use where after the change of use takes place the regulatory reform fire safety order 2005 will apply or continue to apply to the building and the responsible person has the meaning given in the article three of the regulatory reform fire safety order 2005 so section 19 fire safety information like with the consideration of the volume one of the approved document that deals with dwellings the requirement for information is universal throughout information is essential to allow for the safe operation maintenance and assessment of the fire safety system of the property understanding of the fire strategy and to carry out an effective fire risk assessment the amount of information needed depends on the complexity and height of the building but generally is concern in essential information for all buildings falling under the regulatory reform fire safety order 2005 and enhanced for higher risk buildings so which building fall under this consideration basically all buildings but the individual private dwellings so an so an individual house or an individual flood if there are more than one interest or users in the building the fire risk need to be identified and managed respons responsibility for the safety assigned and everyone informed I will not reiterate the least of aspects to consider you can listen to this in the last part of the volume one podcast or read in the [Music] document so this is it folks approve document B Volume 2 Fire Safety in building ENT dwellings is now under your belt this concludes the approved document B series but let's recap this one the requirement B3 concerning internal fire spread structure mandates that buildings be designed to maintain stability during a fire resist fire spread between sh walls and inhibit internal fire spread through compared mization and suppression systems this requirement ensures that buildings with stand fire long enough for safe evacuation and firefighting operations emphasizing compartmentation fire suppression systems and control of fire spread within concealed spaces loadbearing elements of structure fire resistant requirements for structural elements are detailed in appendix B elements essential for structural inter intergrity uh Paramount single story buildings generally don't need Fire Protection unless they support a compartment structure rise storage areas in single story buildings might require additional protection walls and Floors that separate buildings of different uses within a building must act as a compartment walls compartmentation generally extends throughout the entire height of the building or a full story special fire hazards require riry construction enclosures fire those protected protected shaft and appropriate fire stopping measures must be integrated to restrict fire spread sprinklers are required for buildings with top stories over 30 m above ground cavities cavity barriers are necessary to prevent prevent fire spread through concealed spaces with specific rules for large Hidden spaces protection of openings and fire stopping deals with all things that go through the compartment walls and that needs to be fire stopped or sealed with guidance that ADH to strict material and S guidelines car par I either open sided with that require natural ventilation and close sided which may need enhan fire resistant and mechanical ventilation and the installation need to adhere to standards like PS 13661 12101 or 7346 external walls and roofs must resist fire spread considering the building's height use and position regulation 7 mandates the use of appropriate materials and workmanship ensuring external ws and un and attachments comply with fire safety classifications except for specified exemptions buildings must be provided adequate access for fire appliances and firefighters uring internal fire facilities and ventilation for heat and smoke vehicle access firan and hydrant must be pled according to specific guidelines especially for buildings Without fire Mains or with extensive perimeters regulation 38 deals with relevant fire safety information that needs to be provided to the responsible person upon the completion or occupation of the building this includes design and construction details and information necessary for safe operation and maintenance particularly for buildings under the regulatory reform fire safety order 2005 which in the case of bues other than well will be all of them in the next episode we will move to the approved document C side preparation and resistance to contaminants and moisture [Music] I hope you enjoyed this episode and that the consideration of the approved document B fire safety Volume 2 requirements now are now more clear and comprehendible for you you see if you know the lot about the dwellings and flats you pretty much know all the rest if you have any question reach out to me on Linkin or send me an email I'm more than happy to help you out in bit now we deal with planning designing a many of your projects and we are always glad to facilitate a free in initial consultation to steer you in the right direction visit www. bitn now.co and reach out to us whether your question is if we can help you with your project or what should I do we will be able to give you a piece of non obligatory advice at bitna we help our clients design and execute their dream homes or Investments if your building is falling apart we can also help investigate the reasons behind it and to provide you with an appropriate strategy design and specifications for the for the repair thank you again for listening please voice up your opinions I'm waiting for you on LinkedIn and I want to hear from you see you next week remember Bytnar Designs the World Around You, Toodloo!
Piotr Bytnar BEng (Hons) MSc CEng MIStructE
Chartered Structural Engineer who deals with the Architecture of buildings. His Master's Studies led him to an in-depth understanding of risk and contract arrangements in construction as well as specialist knowledge in soil mechanics.
He and his team help homeowners and property developers to design and deliver construction projects reducing waste in time and the cost. He believes that the construction project is an iterative process that can be well managed and it is best managed if all the aspects of the project definition and management are dealt with in-house or coordinated by one organisation. His team works to all stages of RIBA and ISTRUCTE stages of work and enables contractors to deliver projects on-site providing risk evaluations, methodologies for execution of works and temporary works designs.
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